Arianna Huffington to speak at Commonwealth Club

Arianna Huffington, co-founder and editor in chief of The Huffington Post and author of “Third World America,” discusses what she views as the disappearing middle class. [6:30 p.m., Commonwealth Club, 595 Market St., S.F.]

Loteria celebration: The San Francisco Center for the Book hosts “Loteria Live!” The celebration features letterpress prints and activities inspired by the card game. [6 to 8 p.m., 300 De Haro St., S.F.]

Anna Halprin: The dance artist, whose career spans 70 years, conducts a presentation of her work and practice, followed by a master class. [5:30 p.m., USF, Lone Mountain Studio Theater, 2800 Turk Blvd., S.F.]